Is a grease pan needed in a reverse flow

So I'm a newbie here but I have been researching smokers and construction on this site and have learned a lot.  I have determined I am going to build reverse flow out of 30 gallon air tank I have, so by no means a giant, just something for the deck.  Anyway I cant seem to find out about the grease pan.  I understand that the baffle plate can act as a grease drip pan but do people generally have a tube catch it as it drips off the end and run outside the bottom of the smoker (probably letting heat from the baffle plate escape) or simply put a drip pan inside the smoker? or is it not needed at all?  Thanks